1. Field of the Invention
The present invention relates to a linear ball bearing mounting flange, and a method of fabricating a linear ball bearing with a flange.
2. Description of the Prior Art
Linear ball bearings have been extensively used for industrial robots, measuring devices, medical devices, computer terminal devices, and the like. In general, such a linear ball bearing has an annular groove provided around an outer periphery of each end portion of an outer cylinder, as disclosed in Japanese Patent Laid-open No. Hei 3-14907, wherein the linear ball bearing is mounted on a machine or apparatus by inserting the outer cylinder in a hole formed in the machine or apparatus and fixedly inserting an elastic ring or the like in the annular groove. In recent years, however, linear ball bearings of a different type have come to be widely used, in which a flange for mounting the bearing on a machine or apparatus is previously provided around an outer cylinder, wherein the linear ball bearing is mounted on the machine or apparatus by means of the flange mounted on the end portion of the outer cylinder.
In fabrication of such a linear ball bearing with a flange, a flange has been mounted on an outer cylinder of the linear ball bearing by screwing or brazing.
FIG. 11(a) is a view illustrating a method of mounting a flange on an outer cylinder of a bearing by screwing, and FIG. 11(b) is an enlarged view of an essential portion in FIG. 11(a); and FIG. 12(a) is a view illustrating a method of mounting the flange on the outer cylinder of the bearing by brazing; and FIG. 12(b) is an enlarged view of an essential portion in FIG. 12(a). In these figures, reference numeral 1 indicates an outer cylinder of a linear ball bearing; 2 is a linear ball bearing mounting flange having mounting holes 2a; 11 is a screw portion between the flange 2 and the outer cylinder 1; and 12 is a brazing portion between the flange 2 and the outer cylinder 1.
The screw portion used for mounting the flange on the linear ball bearing is obtained by screwing a threaded portion 1a formed around the outer cylinder 1 of the linear ball bearing with a threaded portion 2b formed around the flange 2.
The mounting method by screwing, however, has the following problems that:
(1) since an end portion 1b of the outer cylinder 1 of the linear ball bearing is structurally thinned, it is possibly cracked; PA1 (2) the screw portion 11 is liable to be loosened when the linear ball bearing is applied with an impact force; and PA1 (3) when screwed around the outer cylinder, the flange is often bent, that is, the screwing angle of the flange cannot be kept constant, so that there occur variations in machining allowance in the step of machining the flanges at right angles, resulting in the poor productivity. PA1 (1) since the outer cylinder 1 is press-fitted in the flange 2, the inside diameter of the flange 2 and the outside diameter of the outer cylinder 1 must be finished at high accuracies respectively, resulting in the increased cost of each product; PA1 (2) since being heat-treated together with the outer cylinder 1, the flange 2 is liable to be deformed, so that there occur variations in machining allowance in the step of machining the flanges at right angles, resulting in the poor productivity; and PA1 (3) the work for setting a brazing material in the brazing step must be performed for each product, resulting in poor productivity. PA1 (1) A linear ball bearing mounting flange, which is provided on at least one end of an outer cylinder of a linear ball bearing and is used for mounting the linear ball bearing on a machine or apparatus, the flange including: a flange-shaped structure having a thick wall and provided separately from the outer cylinder, the flange-shaped structure having an annular recess extending from one end surface of the flange-shaped structure along the inner peripheral surface thereof; a peripheral wall on the inner peripheral side of the recess, which has a jagged structure in which projections and recesses are alternately arranged along the circumferential direction; and a locking piece projecting inward from the inner peripheral wall, which is formed at the leading end of each of the projecting portions of the jagged structure. PA1 (2) In a linear ball bearing with a flange described in (1), the flange-shaped structure includes at least three pieces of the projecting portions. PA1 (3) In a linear ball bearing with a flange described in (1), the flange-shaped structure has a partially circular shape in a front view, in which two circular-arc portions are cut off from a circular shape by two straight lines parallel to each other. PA1 (4) In a linear ball bearing with a flange described in (1), (2) or (3), the flange-shaped structure is made from a synthetic resin. PA1 (5) A method of fabricating a linear ball bearing with a flange in which a flange is provided on at least one end of an outer cylinder of a linear ball bearing and is used for mounting the linear ball bearing on a machine or apparatus, including the steps of inserting the flange-shaped structure described in (1), (2) or (3) around an end portion of the outer cylinder and locking locking pieces of the flange-shaped structure in an annular groove provided around the outer cylinder. PA1 (6) A method of fabricating a linear ball bearing with a flange in which a flange is provided on at least one end of an outer cylinder of a linear ball bearing and is used for mounting the linear ball bearing on a machine or apparatus, including the steps of inserting the flange-shaped structure described in (1), (2) or (3) around an end portion of the outer cylinder, engaging locking pieces of the flange-shaped structure in an annular groove provided around the outer cylinder, and press-fitting a wedge-like member in the annular groove for reinforcing the locking of the locking pieces with the annular groove. PA1 (7) In a linear ball bearing described in (5) or (6), the flange-shaped structure is made from a synthetic resin.
To solve the above problems of the mounting method by screwing, the mounting method by brazing has been adopted; however, such a method has also the following problems that:
In general, the flange integrated with the outer cylinder of the linear ball bearing has other problems that the outer periphery of the linear ball bearing cannot be continuously ground because of the presence of the flange; the assembling direction is limited because of the presence of the flange, resulting in the degraded workability; and since the linear ball bearing integrated with the flange has a T-shape, it is difficult to align the linear ball bearings in line because of the unstable postures when being transferred between fabrication steps.